RCE in Python Software Foundation Cpython
CVE-2026-4786
Mitgation of CVE-2026-4519 was incomplete. If the URL contained "%action" the mitigation could be bypassed for certain browser types the "webbrowser.open()" API could have commands injected into the underlying shell. See CVE-2026-4519 for details.
Vulnerability class: Command Injection (OS Command Injection)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.1 (High). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:L.
EPSS exploit prediction
EPSS: 0.005 (39.3th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 39th percentile — 39.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.005 · change: +0.002
Affected products
- Python Software Foundation Cpython — versions 0, 3.13.0, 3.11.0
Weakness classification (CWE)
References
- github.com/python/cpython/pull/148170 (patch)
- github.com/python/cpython/issues/148169 (issue-tracking)
- mail.python.org/archives/list/security-announce@python.org/thread/JQDUNJVB4AQNT… (vendor-advisory)
- github.com/python/cpython/commit/c5767a72838a8dda9d6dc5d3558075b055c56bca (patch)
- github.com/python/cpython/commit/d22922c8a7958353689dc4763dd72da2dea03fff (patch)
- github.com/python/cpython/commit/f4654824ae0850ac87227fb270f9057477946769 (patch)
- github.com/python/cpython/commit/28b4ad38067bbdad34edfcd03ad2de5f06387e53 (patch)
- github.com/python/cpython/commit/d6d68494be70bdbda20f89f83801ba52ec37daa4 (patch)
- 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
Frequently asked questions
- What is CVE-2026-4786?
- CVE-2026-4786 is a high-severity vulnerability in Python Software Foundation Cpython, classified under Command Injection. CVSS score: 7.1/10. Published 2026-04-13.
- How severe is CVE-2026-4786?
- High severity. CVSS v3 base score is 7.1 out of 10.